Motor neurone disease (MND) is a rare, serious and incurable condition where over time, the nerves in the brain and spine experience a progressive loss of function (neurodegeneration).
Specifically, nerve cells known as motor neurones are affected by MND.
What are motor neurones?
Motor neurones are specialised nerve cells that control important voluntary muscle activity, such as:
- walking,
- speaking,
- breathing, and
- swallowing.
Loss of motor neurone function can lead to weakness and wasting of the muscles, increasing loss of mobility in the limbs and difficulties with speech, swallowing and breathing.
How common is motor neurone disease?
MND is one of the rarest neurological conditions (conditions that affect the nervous system).
MND mainly affects adults who are over 40 and most cases develop in people between 50 and 70 years of age. However, MND can affect adults under the age of 40.
Men account for 60% of all cases of MND, with women accounting for the remaining 40%.
The cause (or causes) of MND are unknown, but it seems likely that genes play a factor, at least in some people with the condition. This is because 10% of people who develop MND also have a close family relative with the condition.
Types of motor neurone disease
There are three main types of MND:
- amyotrophic lateral sclerosis (ALS) - is the most common form of MND and accounts for 60-70% of cases,
- progressive bulbar palsy (PBP) - accounts for 20% of MND cases, and
- progressive muscular atrophy (PMA) - accounts for 10% of cases.
The symptoms of all three forms of MND are similar, although there is a difference in how quickly each type progresses.
There is also a very rare form of MND known as primary lateral sclerosis. Unlike other forms of MND, primary lateral sclerosis is not fatal, although there have been some cases when primary lateral sclerosis developed into ALS.
Outlook
In terms of survival rates, the outlook for MND is very poor. The facts are that:
- most people with ALS die within two to five years after the start of symptoms,
- most people with PBP die within six months to three years after the start of symptoms, and
- the outlook for PMA is slightly better, with an average survival rate of five to 10 years.
Although the outlook for most cases of MND is poor, a minority of people with the condition survive much longer than the timescales stated above. For example, the scientist Steven Hawkings has MND, and was diagnosed over 40 years ago.
In terms of quality of life, the outlook for people living with MND is not as bleak as many people imagine. While MND cannot be cured, its symptoms can be treated and some people with the condition are able to maintain a fairly independent lifestyle for a number of years.
Common misconception
A number of recent high-profile news stories have involved people with MND attempting to fight a legal battle in order to obtain the right to euthanasia or assisted suicide. This has led to a widespread misconception that people with MND face the prospect of a painful and traumatic death from choking, malnutrition or suffocation.